The heating value of a volume of natural gas is determined by multiplying the Mcf volume times the appropriate Btu factor.

Btu factors are either presented as Btu per Cf or Btu per Mcf.  If the Btu factor has 3 or 4 places to the left of the decimal point (for example, 1125.5 or 985.5), then the Btu factor is presented as Btu per Cf.  If the Btu factor has 0 or 1 places to the left of the decimal (for example, 1.1255 or 0.9855), then the Btu factor is presented as Btu per Mcf.

General Rule: Both the Mcf volume and the Btu Factor must be stated at the same conditions of pressure base and temperature and the Btu factor must be computed so as to derive the correct heating value based on whether the gas is dry or saturated.

Formulas:

MBtu = 1,000Btu (note: MBtu is not commonly used)

MMBtu = 1,000Mbtu or 1,000,000Btu

Btu per Mcf = Btu per Cf divided by 1,000

MMBtu = Mcf times Btu per Cf divided by 1,000 or

               Mcf times Btu per Mcf 

Calculation Examples:

1,000Mcf times 1100 Btu/Cf divided by 1,000 = 1,100MMBtu

1,000Mcf times 1.100 Btu/Mcf = 1,100MMBtu

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Last updated on March 27, 2002